Scottysan

I'm having a similar problem with my AP4. Mine's a failure to extract, as is shown by the brass when I get it out. It's notched and even torn some of the case rims. My gunsmith said the factory chamber polish is fairly rough on these guns, and he can polish it out better without affecting accuracy. He also said an extractor upgrade would help.

I bought a few when I first got the AP4. No problems with the factory mags, but had all kinds of issues with the c-products. Now, I just use p-mags. :)

been looking at having mine NP3 coated by Robar.

I own an AP4 and my brother in law does too. They both shoot beautifully, especially for carbine length guns. My bro has had his out several times at 200 developing loads for it, and it's still tight... looking to move it to 300 next time.